The present invention relates to a liquid separator of a novel type which is suitable for laboratory use in liquid-liquid or solid-liquid phase separation.
As is well known, the most conventional way to separate a liquid from a second liquid not miscible with the first one is the use of a separatory funnel when the volumes of the liquids to be separated are relatively small as in chemical laboratories. A separatory funnel is a glass-made vessel provided with a stopper at the top and a stopcock at the conically constricted bottom. When a two-phase mixture of liquids is to be separated, the mixture is introduced into the separatory funnel and, when the liquid mixture has been separated into layers by standing for a while, the stopcock at the bottom is opened and the liquid of the lower layer is allowed to flow down out of the separatory funnel. At a moment when the interface of the liquid layers has just arrived at the stopcock, the stopcock is rapidly closed to finish the liquid-liquid phase separation.
The above described laboratory procedure of liquid-liquid separation by use of a separatory funnel has several problems. Firstly, timely closing of the stopcock is essential at just the moment of the arrival of the interface at the stopcock which requires very careful watching of the downward movement of the interface and utmost skillfulness of the operator in handling the stopcock. Secondly, incompleteness in separation is unavoidable because the stopcock has a pore of definite volume for the flow of the liquid and criticality of separation depends on whether the stopcock is closed at a moment when the interface is above the stopcock or in the pore of the stopcock. This problem is of considerable significance, especially, when the volume of either layer is extremely small. Thirdly, phase separation is sometimes incomplete or takes a too long time of standing depending on the relationships in the specific gravities and surface tensions of the liquid phases. In addition, the liquid of the lower layer flowing down out of the separatory funnel is usually received in an open vessel so that considerable loss of the separated liquid takes place by evaporation before completion of flowing down of whole volume of the liquid in the lower layer when it is very volatile. This problem of evaporation loss is particularly serious when the liquid contains a volatile radioactive substance which may cause dangerous environmental pollution.
Further, solid-liquid separation in laboratory procedure is very often, though not always, carried out by use of a filter paper or other filtering material placed on a funnel such as a conical funnel or a Buchner funnel, through which the liquid alone in the solid-liquid mixture passes to flow down. In any case, these funnels are open to the atmosphere so that the problem of the evaporation loss of the liquid is unavoidable.